Collection and Characterization of Wood Decay Fungal Strains for Developing Pure Mycelium Mats

Wood decay fungi (WDF) seem to be particularly suitable for developing myco-materials due to their mycelial texture, ease of cultivation, and lack of sporification. This study focused on a collection of WDF strains that were later used to develop mycelium mats of leather-like materials. Twenty-one WDF strains were chosen based on the color, homogeneity, and consistency of the mycelia. The growth rate of each strain was measured. To improve the consistency and thickness of the mats, an exclusive method (newly patented) was developed. The obtained materials and the corresponding pure mycelia grown in liquid culture were analyzed by both thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) to evaluate the principal components and texture. TGA provided a semi-quantitative indication on the mycelia and mat composition, but it was hardly able to discriminate differences in the production process (liquid culture versus patented method). SEM provided keen insight on the mycelial microstructure as well as that of the mat without considering the composition; however, it was able to determine the hyphae and porosity dimensions. Although not exhaustive, TGA and SEM are complementary methods that can be used to characterize fungal strains based on their desirable features for various applications in bio-based materials. Taking all of the results into account, the Fomitopsis iberica strain seems to be the most suitable for the development of leather-like materials.

Analysis of pigments and damages for the 19th century White-robed Water-moon Avalokitesvara Painting in Gongju Magoksa Temple, Republic of Korea

The White-Robed Water-Moon Avalokiteshvara painting displayed on the rear wall of Daegwangbojeon (main hall) in Magoksa temple, is one of the representative Buddhist paintings in the late nineteenth century of Korea, and a valuable resource for understanding the coloring techniques and characteristics of Buddhist paintings in terms of expression and description in landscape painting. In this painting, the contours and colored surface remain undamaged, but blistering and exfoliation appear on some pigment layers. Furthermore, the partial decomposition of wooden materials due to wood-decay fungi and insect damage were found on the rear wall requiring proper treatment for long-term conservation. As the results of chromaticity and P-XRF analysis regarding the color pigment layer of the painting, the pigments were classified into ten types. The results suggest that the colors other than blue, green, yellow, red, black, and white were prepared by mixing two or more pigments. The types of pigments according to colors, were determined as traditional pigments with azurite; emerald green or clinoatacamite; 0 massicot; minium or hematite; Chinese ink; and kaolin, white lead, and gypsum, respectively. Violet and pink colors were assumed to have been prepared by mixing white with blue and red. In most of these pigments, small amounts of synthetic compositions from the modern era were detected at many points.

Genomic and Transcriptomic Insight of Giant Sclerotium Formation of Wood-Decay Fungi

Many fungi form persistent and dormant sclerotia with compact hardened mycelia during unfavorable circumstances. While most of these sclerotia are small in size, Wolfiporia cocos, a wood-decay fungus, grows into giant sclerotia, which are mainly composed of polysaccharides of linear (1→3)-β-D-glucans. To explore the underlying mechanism of converting sophisticated wood polysaccharides for biosynthesis of highly homogenized glucans in W. cocos, we sequenced and assembled the genome of a cultivated W. cocos strain (WCLT) in China. The 62-Mb haploid genome contains 44.2% repeat sequences, of which, 48.0% are transposable elements (TEs). Contrary to the genome of W. cocos from North America, WCLT has independently undergone a partial genome duplication (PGD) event. The large-scale TE insertion and PGD occurrence overlapped with an archeological Pleistocene stage of low oxygen and high temperature, and these stresses might have induced the differences in sclerotium due to geographical distribution. The wood decomposition enzymes, as well as sclerotium-regulator kinases, aquaporins, and highly expanded gene families such as NAD-related families, together with actively expressed 1,3-β-glucan synthase for sclerotium polysaccharides, all have contributed to the sclerotium formation and expansion. This study shall inspire further exploration on how fungi convert wood into simple glucans in the sclerotium of W. cocos.

Carbon and Oxygen Gas Exchange in Woody Debris: The Process and Climate-Related Drivers

The carbon-to-oxygen relationship and gas exchange balance, organic carbon to CO2 conversion intensity and efficiency, and their relevance to climate parameters and wood decay fungi were investigated for birch woody debris (WD) in the Mid-Urals mixed pine and birch forests. It was shown that, within the range of temperatures from 10 to 40 °C and relative moisture (RM) of wood of 40% and 70%, aerobic gas exchange was observed in the WD, encompassing the physiologically entwined processes of CO2 emission and O2 uptake. Their volumetric ratio (0.9) confirmed that (1) the WD represents a globally significant CO2 source and appropriate O2 consumer and (2) the oxidative conversion of organic carbon is highly efficient in the WD, with an average ratio of CO2 released to O2 consumed equal to 90%. The balance of carbon-to-oxygen gas exchange and oxidizing conversion efficiency in the WD were not affected by either fungal species tested or by moisture or temperature. However, the intensity of gas exchange was unique for each wood decay fungi, and it could be treated as a climate-reliant parameter driven by temperature (Q10 = 2.0–2.1) and moisture (the latter induced a corresponding trend and value changes in CO2 emission and O2 uptake). Depending on the direction and degree of the change in temperature and moisture, their combined effect on the intensity of gas exchange led to its strengthening or weakening; otherwise, it was stabilized. Aerobic respiration of wood decay Basidiomycetes is an essential prerequisite and the major biotic factor in the WD gas exchange, while moisture and temperature are its climatic controllers only.

Degradation ability of wood decay fungi in teak (Tectona grandis L.) wood under storage condition

Aim: The present study was undertaken to provide basic knowledge about the teak woody biomass degradation ability of wood decay fungi. Methodology: Wood decay fungi was isolated from the decayed wood samples collected from teak wood logs. The weight loss of teak wood and moisture content were assessed under in-vitro condition by incubating the teak wood block with the isolated fungi. Further, the secretion of ligninolytic enzymes viz., laccase, lignin peroxidise (LiP) and manganese peroxidase (MnP) produced by wood decay fungi were assessed to understand their degrading ability. Results: Wood decay fungi namely, Daldinia concentrica, Ganoderma lucidum, Lenzites betulina, Ganoderma tsugae, Trametes versicolor and Schizophyllum commune, were isolated from teak wood logs as pure culture and were used for studying their degrading ability. Higher degrading percentage of 10.50 and 12.0 was recorded with L. betulina and T. versicolor inoculated wood blocks on 60th day of incubation. Similarly, the maximum moisture content of 54.45 and 50.00 percent was recorded with L. betulina and T. versicolor at 60th day of incubation in teak wood blocks. Supporting these results, L. betulina showed increased secretion of laccase, LiP and MnP enzyme activity to the level of 0.60, 0.056 and 0.26U ml-1, respectively. Interpretation: The results of the present study gives an understanding on the degrading ability of wood decay fungi which can be used to devise integrated management practices to minimise the losses under storage.

Omics analyses and biochemical study of Phlebiopsis gigantea elucidate its degradation strategy of wood extractives

Wood extractives, solvent-soluble fractions of woody biomass, are considered to be a factor impeding or excluding fungal colonization on the freshly harvested conifers. Among wood decay fungi, the basidiomycete Phlebiopsis gigantea has evolved a unique enzyme system to efficiently transform or degrade conifer extractives but little is known about the mechanism(s). In this study, to clarify the mechanism(s) of softwood degradation, we examined the transcriptome, proteome, and metabolome of P. gigantea when grown on defined media containing microcrystalline cellulose and pine sapwood extractives. Beyond the conventional enzymes often associated with cellulose, hemicellulose and lignin degradation, an array of enzymes implicated in the metabolism of softwood lipophilic extractives such as fatty and resin acids, steroids and glycerides was significantly up-regulated. Among these, a highly expressed and inducible lipase is likely responsible for lipophilic extractive degradation, based on its extracellular location and our characterization of the recombinant enzyme. Our results provide insight into physiological roles of extractives in the interaction between wood and fungi.